Zinc oxide nanoparticles alleviated vanadium-induced inhibition by regulating plant hormone signal transduction and phenylpropanoid biosynthesis in maize seedlings (Zea may L.)

Abstract

Our efforts were to identify the role of zinc oxide nanoparticles (ZnO-NPs) on the growth of maize (Zea may L.) under vanadium (V) stress. Transcriptome analysis was performed on maize leaves subjected to CK, V, and V+ZnO treatments. It was found that the application of ZnO-NPs significantly reduces V accumulation and toxicity in maize. A total of 5441 and 3003 differentially expressed genes (DEGs) were identified in the CK vs. V and V+ZnO vs. V comparisons, respectively. Of these detected genes, 3016 DEGs were specific to CV vs. V, and 608 DEGs were specific to V+ZnO vs V, respectively. These genes were primarily involved in plant hormone signal transduction and phenylpropanoid biosynthesis pathways. Under V treatment, ZnO-NPs caused an up-regulation of SAUR, AUX/IAA, ARRs, GID1, and BRIIs, which resulted in high levels of IAA, CTK, GA, BRs, and JAs in maize seedlings compared to those without ZnO-NPs. The addition of ZnO-NPs also leads to a significant decrease in total phenolics and lignin contents in maize seedlings by down-regulating CCR, HCT, CAD, 4CL, and C4H genes compared to those without ZnO-NPs. Overall, the findings suggest that ZnO-NPs can improve V-induced growth suppression by changing the expression of selected genes and constitute a simple and efficient strategy for alleviating V toxicity in high-V soils.